1. Field of the Invention
The present invention relates generally to, among other things, utility devices, such as, for example, utility vehicles, including, for example, tractors, skid-steer vehicles and/or the like having hydraulic circuits.
2. Discussion of the Background
There are a variety of known utility devices, such as, e.g., utility vehicles, having hydraulic circuits, such as, e.g., for hydraulically powering tools. In many instances, utility vehicles are often used for construction and/or other utilitarian purposes, such as, e.g., for lifting, pushing, scraping, digging, plowing and/or various other purposes. As shown in FIG. 1, in some illustrative examples, a utility vehicle 100 can include, e.g., a) a main body 105 having at least one seat for a vehicle operator (such as, for example, a seat located within a protective cab 110), b) wheels 120 and/or other supports mounted on the body portion for supporting the same, and c) one or more utility mechanism 130 mounted to the vehicle (such as, e.g., via a utility boom 140). Often, the utility mechanism(s) can be hydraulically powered and/or controlled. In some illustrative cases, the utility mechanism(s) can include, e.g., one or more of the following: a) an auger; b) a tiller, c) a rotary broom, d) a backhoe; e) a dozer blade; f) a bucket; g) a fork (e.g., for pallets, manure or the like); h) a grinder; i) a rake; j) shears; k) a roller; l) spike (e.g., for bails of hay or the like); m) a jig boom; n) a scraper; o) a tree spade; p) a plow; q) a mower; r) a trencher; s) a four-in-one bucket; and/or various other utility mechanisms. In some instances, the vehicle is adapted such that various utility mechanisms can be replaced, interchanged, upgraded and/or the like. In this manner, in some instances, a basic vehicle can be adapted or configured to perform specific tasks (such as, e.g., by attaching a new utility mechanism to the vehicle).
Because these vehicles are often used for work related purposes, improvements that can reduce manufacturing costs, increase longevity and/or durability, increase performance and/or that can provide other advances can be desirable.
FIG. 5 is a schematic diagram showing one illustrative system similar to that of certain background art that is used to operate a hydraulic cylinder HC of a utility vehicle. In this system, if the fluid in line L2 is high pressure, the flow will be from a female coupler (shown) toward a male coupler (shown) and the fluid will bypass the pilot check valve PCV through the check valve CV1 and will enter the motor HM via a port M2. The fluid will exit the port M1 at a low pressure and will return to the primary system via line L1 and the male coupler. If the solenoid directional valve SDV is energized, there will be high-pressure fluid in both ports A and B of the solenoid valve. This will render the hydraulic cylinder immovable. However, if the fluid flow is reversed, energizing the solenoid valve SDV will allow pressurized fluid (pressure derived from maintaining the pilot check valve PCV in an open position) to flow through port B of solenoid directional valve SDV and exit port C or D depending on the direction the solenoid directional valve SDV is shifted. This action diverts fluid via the shuttle valve and the pilot line PL1 to close the pilot check valve PCV. Flow continues toward either ports H1 or H2 of the hydraulic cylinder HC depending on which direction the solenoid directional valve SDV is shifted and moves the actuator of the hydraulic cylinder HC. Once the pilot check valve PCV is closed, enough pressure is available to allow the actuator in the hydraulic cylinder HC to function (e.g., reciprocate by flow of fluid in and out of ports H1 and H2). Depending on the pressure required to move the actuator of the hydraulic cylinder HC, the hydraulic motor HM experiences a corresponding loss of available pressure. Moreover, once the actuator comes to a limit of its travel, the hydraulic motor HM will stop rotating.
FIG. 6 is a schematic diagram showing another circuit that functions generally similarly to the circuit shown in FIG. 5. The circuits shown in FIGS. 5 and 6 have a number of deficiencies, such as, e.g., deficiencies described below.
With reference to the system depicted in FIG. 5, by way of example, one or more of the following deficiencies may be found.
First, the line pressure loss to keep the pilot check valve PCV open can cause inefficiencies and/or unnecessary system heating.
Second, after the solenoid is energized, all of the flow from the hydraulic motor is diverted through a restrictor and then through the solenoid directional valve SDV and the hydraulic cylinder HC. This can, e.g., unduly slow the hydraulic motor HM and/or can cause unnecessary system heating.
Third, at the time the hydraulic cylinder HC reaches an actuator travel limit, the hydraulic motor HM will stop. This will cause inefficiencies for the operator of the prime mover (such as, e.g., a prime mover effecting overall vehicle movement). The forward motion of the prime mover may have to be altered to allow the unit to perform a uniform operation.
Fourth, the hydraulic cylinder HC can only be operated for one direction of rotation of the hydraulic motor HM.
There remains a need for, among other things, utility devices, such as, e.g., utility vehicles, having utility mechanisms with improved hydraulic systems.